Move JFR functionality into junit-platform-launcher (#4674)

* Avoid storing JFR events when they are disabled
* Only fill JFR events if they're about to be committed
* Move JFR event generating listeners into junit-platform-launcher
* Make JFR optional
* Remove unnecessary concurrency handling

Resolves #4579.

Author: marcphilipp

build.gradle.kts

@@ -22,7 +22,6 @@ val platformProjects by extra(listOf(
 		projects.junitPlatformConsole,
 		projects.junitPlatformConsoleStandalone,
 		projects.junitPlatformEngine,
-		projects.junitPlatformJfr,
 		projects.junitPlatformLauncher,
 		projects.junitPlatformReporting,
 		projects.junitPlatformSuite,

documentation/documentation.gradle.kts

@@ -81,12 +81,6 @@ dependencies {
 		because("Jimfs is used in src/test/java")
 	}
 
-	if (java.toolchain.implementation.orNull == JvmImplementation.J9) {
-		testRuntimeOnly(libs.jfrPolyfill) {
-			because("OpenJ9 does not include JFR")
-		}
-	}
-
 	standaloneConsoleLauncher(projects.junitPlatformConsoleStandalone)
 }
 

documentation/src/docs/asciidoc/release-notes/release-notes-6.0.0-M1.adoc

@@ -49,6 +49,10 @@ repository on GitHub.
   `--h` (rather than `-h`) or `-help` (rather than `--help`).
 * The `junit-platform-runner` module that provided the JUnit 4 based `JUnitPlatform`
   runner has been discontinued.
+* The `junit-platform-jfr` module that provided custom Java Flight Recorder (JFR) events
+  for test discovery and execution has been discontinued. Instead, the functionality is
+  now available directly in `junit-platform-launcher` without requiring an additional
+  dependency.
 * Support for Maven Surefire/Failsafe versions less than 3.0.0 has been dropped.
 * The following deprecated APIs have been removed:
   - `ReflectionSupport.loadClass(String)` method

documentation/src/docs/asciidoc/user-guide/appendix.adoc

@@ -65,10 +65,6 @@ Please refer to the corresponding sections for <<running-tests-build-maven-bom,
     directory. See <<running-tests-console-launcher>> for details.
   `junit-platform-engine`::
     Public API for test engines. See <<launcher-api-engines-custom>> for details.
-  `junit-platform-jfr`::
-    Provides a `LauncherDiscoveryListener` and `TestExecutionListener` for Java Flight
-	Recorder events on the JUnit Platform. See <<running-tests-listeners-flight-recorder>>
-	for details.
   `junit-platform-launcher`::
     Public API for configuring and launching test plans -- typically used by IDEs and
     build tools. See <<launcher-api>> for details.

documentation/src/docs/asciidoc/user-guide/running-tests.adoc

@@ -1119,9 +1119,7 @@ to a problem.
 In order to record Flight Recorder events generated while running tests, you need to:
 
 1. Ensure that you are using either Java 8 Update 262 or higher or Java 11 or later.
-2. Provide the `org.junit.platform.jfr` module (`junit-platform-jfr-{version}.jar`)
-   on the class-path or module-path at test runtime.
-3. Start flight recording when launching a test run. Flight Recorder can be started via
+2. Start flight recording when launching a test run. Flight Recorder can be started via
    java command line option:
 
    -XX:StartFlightRecording:filename=...

documentation/src/plantuml/component-diagram.puml

@@ -20,7 +20,6 @@ package org.junit.platform {
     [junit-platform-commons] as commons
     [junit-platform-console] as console
     [junit-platform-engine] as engine
-    [junit-platform-jfr] as jfr
     [junit-platform-launcher] as launcher
     [junit-platform-reporting] as reporting
     [junit-platform-suite] as suite

gradle/libs.versions.toml

@@ -42,7 +42,6 @@ groovy2-bom = { module = "org.codehaus.groovy:groovy-bom", version = "2.5.23" }
 hamcrest = { module = "org.hamcrest:hamcrest", version = "3.0" }
 jackson-dataformat-yaml = { module = "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml", version.ref = "jackson" }
 jackson-module-kotlin = { module = "com.fasterxml.jackson.module:jackson-module-kotlin", version.ref = "jackson" }
-jfrPolyfill = { module = "org.gradle.jfr.polyfill:jfr-polyfill", version = "1.0.2" }
 jfrunit = { module = "org.moditect.jfrunit:jfrunit-core", version = "1.0.0.Alpha2" }
 jimfs = { module = "com.google.jimfs:jimfs", version = "1.3.0" }
 jmh-core = { module = "org.openjdk.jmh:jmh-core", version.ref = "jmh" }

gradle/plugins/common/src/main/kotlin/junitbuild.testing-conventions.gradle.kts

@@ -201,13 +201,9 @@ dependencies {
 	testImplementation(project(":junit-jupiter"))
 
 	testRuntimeOnly(project(":junit-platform-engine"))
-	testRuntimeOnly(project(":junit-platform-jfr"))
 	testRuntimeOnly(project(":junit-platform-reporting"))
 
 	testRuntimeOnly(bundleFromLibs("log4j"))
-	testRuntimeOnly(dependencyFromLibs("jfrPolyfill")) {
-		because("OpenJ9 does not include JFR")
-	}
 	testRuntimeOnly(dependencyFromLibs("openTestReporting-events")) {
 		because("it's required to run tests via IntelliJ which does not consumed the shadowed jar of junit-platform-reporting")
 	}

junit-platform-commons/src/main/java/module-info.java

@@ -50,7 +50,6 @@
 			org.junit.jupiter.params,
 			org.junit.platform.console,
 			org.junit.platform.engine,
-			org.junit.platform.jfr,
 			org.junit.platform.launcher,
 			org.junit.platform.reporting,
 			org.junit.platform.suite.api,

junit-platform-jfr/junit-platform-jfr.gradle.kts

@@ -25,6 +25,7 @@
 
 	requires static transitive org.apiguardian.api;
 	requires static org.jspecify;
+	requires static jdk.jfr;
 
 	requires transitive java.logging;
 	requires transitive org.junit.platform.commons;

junit-platform-jfr/src/main/java/module-info.java

@@ -38,7 +38,6 @@ class ClasspathAlignmentChecker {
 		"org.junit.platform.commons", //
 		"org.junit.platform.console", //
 		"org.junit.platform.engine", //
-		"org.junit.platform.jfr", //
 		"org.junit.platform.launcher", //
 		"org.junit.platform.reporting", //
 		"org.junit.platform.suite.api", //

junit-platform-jfr/src/main/java/org/junit/platform/jfr/package-info.java

@@ -35,6 +35,7 @@
 import org.junit.platform.launcher.LauncherSessionListener;
 import org.junit.platform.launcher.PostDiscoveryFilter;
 import org.junit.platform.launcher.TestExecutionListener;
+import org.junit.platform.launcher.jfr.JfrUtils;
 
 /**
  * Factory for creating {@link Launcher} instances by invoking {@link #create()}
@@ -139,6 +140,7 @@ private static DefaultLauncher createDefaultLauncher(LauncherConfig config,
 		Set<TestEngine> engines = collectTestEngines(config);
 		List<PostDiscoveryFilter> filters = collectPostDiscoveryFilters(config);
 		DefaultLauncher launcher = new DefaultLauncher(engines, filters, sessionLevelStore);
+		JfrUtils.registerListeners(launcher);
 		registerLauncherDiscoveryListeners(config, launcher);
 		registerTestExecutionListeners(config, launcher, configurationParameters);
 

junit-platform-jfr/src/main/resources/META-INF/services/org.junit.platform.launcher.LauncherDiscoveryListener

@@ -8,14 +8,12 @@
  * https://www.eclipse.org/legal/epl-v20.html
  */
 
-package org.junit.platform.jfr;
+package org.junit.platform.launcher.jfr;
 
-import static java.util.Objects.requireNonNull;
-import static org.apiguardian.api.API.Status.STABLE;
+import static org.apiguardian.api.API.Status.INTERNAL;
 
+import java.util.HashMap;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.atomic.AtomicReference;
 
 import jdk.jfr.Category;
 import jdk.jfr.Event;
@@ -40,50 +38,62 @@
  * @since 1.8
  * @see <a href="https://openjdk.java.net/jeps/328">JEP 328: Flight Recorder</a>
  */
-@API(status = STABLE, since = "1.11")
-public class FlightRecordingDiscoveryListener implements LauncherDiscoveryListener {
+@API(status = INTERNAL, since = "6.0")
+class FlightRecordingDiscoveryListener implements LauncherDiscoveryListener {
 
-	private final AtomicReference<@Nullable LauncherDiscoveryEvent> launcherDiscoveryEvent = new AtomicReference<>();
-	private final Map<org.junit.platform.engine.UniqueId, EngineDiscoveryEvent> engineDiscoveryEvents = new ConcurrentHashMap<>();
+	private final Map<org.junit.platform.engine.UniqueId, EngineDiscoveryEvent> engineDiscoveryEvents = new HashMap<>();
+	private @Nullable LauncherDiscoveryEvent launcherDiscoveryEvent;
 
 	@Override
 	public void launcherDiscoveryStarted(LauncherDiscoveryRequest request) {
-		LauncherDiscoveryEvent event = new LauncherDiscoveryEvent();
-		event.selectors = request.getSelectorsByType(DiscoverySelector.class).size();
-		event.filters = request.getFiltersByType(DiscoveryFilter.class).size();
-		event.begin();
-		launcherDiscoveryEvent.set(event);
+		var event = new LauncherDiscoveryEvent();
+		if (event.isEnabled()) {
+			event.begin();
+			this.launcherDiscoveryEvent = event;
+		}
 	}
 
 	@Override
 	public void launcherDiscoveryFinished(LauncherDiscoveryRequest request) {
-		requireNonNull(launcherDiscoveryEvent.getAndSet(null)).commit();
+		LauncherDiscoveryEvent event = this.launcherDiscoveryEvent;
+		this.launcherDiscoveryEvent = null;
+		if (event != null && event.shouldCommit()) {
+			event.selectors = request.getSelectorsByType(DiscoverySelector.class).size();
+			event.filters = request.getFiltersByType(DiscoveryFilter.class).size();
+			event.commit();
+		}
 	}
 
 	@Override
 	public void engineDiscoveryStarted(org.junit.platform.engine.UniqueId engineId) {
-		EngineDiscoveryEvent event = new EngineDiscoveryEvent();
-		event.uniqueId = engineId.toString();
-		event.begin();
-		engineDiscoveryEvents.put(engineId, event);
+		var event = new EngineDiscoveryEvent();
+		if (event.isEnabled()) {
+			event.begin();
+			this.engineDiscoveryEvents.put(engineId, event);
+		}
 	}
 
 	@Override
 	public void engineDiscoveryFinished(org.junit.platform.engine.UniqueId engineId, EngineDiscoveryResult result) {
-		EngineDiscoveryEvent event = engineDiscoveryEvents.remove(engineId);
-		event.result = result.getStatus().toString();
-		event.commit();
+		EngineDiscoveryEvent event = this.engineDiscoveryEvents.remove(engineId);
+		if (event != null && event.shouldCommit()) {
+			event.uniqueId = engineId.toString();
+			event.result = result.getStatus().toString();
+			event.commit();
+		}
 	}
 
 	@Override
 	public void issueEncountered(org.junit.platform.engine.UniqueId engineId, DiscoveryIssue issue) {
-		DiscoveryIssueEvent event = new DiscoveryIssueEvent();
-		event.engineId = engineId.toString();
-		event.severity = issue.severity().name();
-		event.message = issue.message();
-		event.source = issue.source().map(Object::toString).orElse(null);
-		event.cause = issue.cause().map(ExceptionUtils::readStackTrace).orElse(null);
-		event.commit();
+		var event = new DiscoveryIssueEvent();
+		if (event.shouldCommit()) {
+			event.engineId = engineId.toString();
+			event.severity = issue.severity().name();
+			event.message = issue.message();
+			event.source = issue.source().map(Object::toString).orElse(null);
+			event.cause = issue.cause().map(ExceptionUtils::readStackTrace).orElse(null);
+			event.commit();
+		}
 	}
 
 	@Category({ "JUnit", "Discovery" })